<template>
  <div>
    <div tag="div" @click="back" class="header-abs" v-show="showAbs">
      <div class="iconfont icon-arrow-left-2 header-abs-back"></div>
    </div>
  </div>
</template>

<script>
export default {
  name: "DetailHeader",
  data() {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 1,
      },
    };
  },
  methods: {
    back() {
      this.$router.back();
    },
    handleScroll() {
      const top =
        document.documentElement.scrollTop ||
        document.body.scrollTop ||
        window.pageYOffset;
      console.log(top);
      if (top > 60) {
        let opacity = top / 140;
        opacity = opacity > 1 ? 1 : opacity;
        this.opacityStyle = { opacity };
        this.showAbs = false;
      } else {
        this.showAbs = true;
      }
    },
  },
  mounted() {
    window.addEventListener("scroll", this.handleScroll);
  },
  destroyed() {
    window.removeEventListener("scroll", this.handleScroll);
  },
};
</script>

<style lang="scss" scoped>
.header-abs {
  position: absolute;
  left: 0.2rem;
  top: 0.2rem;
  width: 0.8rem;
  height: 0.8rem;
  line-height: 0.8rem;
  border-radius: 0.4rem;
  text-align: center;
  background: rgba(0, 0, 0, 0.4);
  .header-abs-back {
    color: #fff;
    font-size: 0.4rem;
  }
}

.header-fixed {
  z-index: 2;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 8vh;
  line-height: 8vh;
  text-align: center;
  color: #fff;
  background: #ddd;
  font-size: 0.32rem;
  .header-fixed-back {
    position: absolute;
    top: 0;
    left: 0;
    width: 0.64rem;
    text-align: center;
    font-size: 0.4rem;
    color: #fff;
  }
}
</style>
